KVM: MMU: hypercall based pte updates and TLB flushes

Hypercall based pte updates are faster than faults, and also allow use
of the lazy MMU mode to batch operations.

Don't report the feature if two dimensional paging is enabled.

[avi:
 - one mmu_op hypercall instead of one per op
 - allow 64-bit gpa on hypercall
 - don't pass host errors (-ENOMEM) to guest]

[akpm: warning fix on i386]

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Avi Kivity <avi@qumranet.com>

1 files changed, 17 insertions, 1 deletions

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 03ba402c476a..63afca1c295f 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -832,6 +832,9 @@ int kvm_dev_ioctl_check_extension(long ext)
         case KVM_CAP_NR_MEMSLOTS:
                 r = KVM_MEMORY_SLOTS;
                 break;
+        case KVM_CAP_PV_MMU:
+                r = !tdp_enabled;
+                break;
         default:
                 r = 0;
                 break;
@@ -2452,9 +2455,19 @@ int kvm_emulate_halt(struct kvm_vcpu *vcpu)
 }
 EXPORT_SYMBOL_GPL(kvm_emulate_halt);
 
+static inline gpa_t hc_gpa(struct kvm_vcpu *vcpu, unsigned long a0,
+                           unsigned long a1)
+{
+        if (is_long_mode(vcpu))
+                return a0;
+        else
+                return a0 | ((gpa_t)a1 << 32);
+}
+
 int kvm_emulate_hypercall(struct kvm_vcpu *vcpu)
 {
         unsigned long nr, a0, a1, a2, a3, ret;
+        int r = 1;
 
         kvm_x86_ops->cache_regs(vcpu);
 
@@ -2476,6 +2489,9 @@ int kvm_emulate_hypercall(struct kvm_vcpu *vcpu)
         case KVM_HC_VAPIC_POLL_IRQ:
                 ret = 0;
                 break;
+        case KVM_HC_MMU_OP:
+                r = kvm_pv_mmu_op(vcpu, a0, hc_gpa(vcpu, a1, a2), &ret);
+                break;
         default:
                 ret = -KVM_ENOSYS;
                 break;
@@ -2483,7 +2499,7 @@ int kvm_emulate_hypercall(struct kvm_vcpu *vcpu)
         vcpu->arch.regs[VCPU_REGS_RAX] = ret;
         kvm_x86_ops->decache_regs(vcpu);
         ++vcpu->stat.hypercalls;
-        return 0;
+        return r;
 }
 EXPORT_SYMBOL_GPL(kvm_emulate_hypercall);